The present invention relates generally to gear-type pumps. More particularly, the present invention relates to a geared feed pump for supplying fuel to a high-pressure fuel pump.
One type of geared feed pump is described in DE 196 25 488 A1. This geared feed pump has a rotary-powered pair of meshed gears arranged in a pump chamber of a housing. The feed pump feeds along fuel from a suction chamber between the perimeters of the gears and opposite-lying peripheral walls of the supply channels formed in the pump chamber into a pressure chamber. One of the gears is secured to a drive shaft, which is rotatably supported in the housing, by means of a hole. The drive shaft projects from the housing and there, is connected to a drive element via an overload-protection device. The overload-protection device has a radial, resilient connecting element, which is arranged on an end area of the drive shaft and pressed into a hole of the drive element. Through the connecting element, the torque transferable from the drive element onto the drive shaft is limited, in that upon exceeding the transferable torque, the drive element is rotatable relative to the drive shaft. In addition, through the connecting element, an equalization of manufacturing tolerance conditional offset and/or sloping position of the rotational axis of the drive element and the drive shaft is made possible. The gear secured on the drive shaft must be arranged with the least possible play for the oppositely lying peripheral wall of the pump chamber, in order to achieve a good efficiency of the geared feed pump. This is due to the rigid securement of the gear on the drive shaft, and whose positioning in the housing, as a result of the existing manufacturing tolerance, is difficult and is only obtainable with a very large expenditure. Moreover, a rigid connection of the gear with the drive shaft, for example, by a press-fit connection, is critical with a gear made from sinter metal, since with this construction, damage to the gear can occur.
In contrast with the above-described device, the geared feed pump of the present invention makes possible an equalization of the manufacturing tolerance of the positioning of the drive shaft and the arrangement of the gear connected to the drive shaft in the pump chamber by at least one connecting element, so that the gear can be arranged in the pump chamber with the required minimal play. In addition, the at least one connecting element forms an overload-protection device through which the torque transferable onto the gear is limited. It is also contemplated that the transferable torque can be increased.
The embodiments of the invention are illustrated in the drawings and described in more detail in the following description.